Debian kernel bugs

Debian kernel bugs

When I run my work laptop (latest Thinkpad Carbon X1) with the kernel from
Testing it fails to resume from suspend about 30% of the time. When I use the
kernel from Stable (with Testing userspace) it runs correctly.

Do you have any ideas for how I could track this down? It fails when it's not
in a state to report what's happening. I don't even know if the problem is
with suspend or resume. When it happens nothing happens at the time it's
supposed to resume and I have to just hold the power button down until it has
a hard reset.

Is there an archive of all the kernels that have been uploaded to Unstable
that I could do a binary search on and find out which version had the change
that broke things for me?

Re: Debian kernel bugs

On Thu, 2019-03-14 at 04:35 +0000, Russell Coker wrote:
> Is there an archive of all the kernels that have been uploaded to Unstable
> that I could do a binary search on and find out which version had the change
> that broke things for me?

snapshots.d.o should have everything, including the ones which went to
experimental etc.

I don't have any specific advice for debugging suspend/resume though,
sorry (I can say it works ok on my 4th gen carbon X1, but I think
that's not the latest by at least a gen if not two).

Re: Debian kernel bugs

On Friday, 15 March 2019 1:44:58 AM AEDT Ian Campbell wrote:
> On Thu, 2019-03-14 at 04:35 +0000, Russell Coker wrote:
> > Is there an archive of all the kernels that have been uploaded to Unstable
> > that I could do a binary search on and find out which version had the
> > change that broke things for me?
>
> snapshots.d.o should have everything, including the ones which went to
> experimental etc.

Thanks for that advice, I've started that process now. Looks like 4.14.0-rc3-
amd64 doesn't hang on suspend, but I need more testing to be sure.

> I don't have any specific advice for debugging suspend/resume though,
> sorry (I can say it works ok on my 4th gen carbon X1, but I think
> that's not the latest by at least a gen if not two).

I think mine is 6th gen. It's a nice system when it's not crashing.

Also I have another problem in that it sometimes locks up when doing video
stuff. That happens both in the Stretch and the Testing kernels so I don't
think it's related to the hang on suspend issue.

Any suggestions on how to debug total video lockups (to the stage that the
caps-lock LED doesn't work)?

Re: Debian kernel bugs

> On Thu, 2019-03-14 at 04:35 +0000, Russell Coker wrote:
> > Is there an archive of all the kernels that have been uploaded to Unstable
> > that I could do a binary search on and find out which version had the
> > change that broke things for me?
>
> snapshots.d.o should have everything, including the ones which went to
> experimental etc.
>
> I don't have any specific advice for debugging suspend/resume though,
> sorry (I can say it works ok on my 4th gen carbon X1, but I think
> that's not the latest by at least a gen if not two).

Thanks for the advice. I did a binary search through the kernels on snapshots
and found that 4.10.0-trunk-amd64 (possibly the earliest one that's later than
Stretch) had the problem too.

Now I'm on 5.0.0-trunk-amd64 which has been going fine for 5 days and probably
has no problems in this regard (usually the problem occurs in 1-2 days but
there's enough variation that it's not impossible I just got lucky). I guess
I can track Unstable for kernel releases on my laptop until Bullseye is
released.

As an aside, the Stretch kernel lacks the NNP SE Linux functionality that is
in the Buster kernel which means that some daemons like mysqld run with
elevated privileges. I'll blog about this shortly. The summary is that a
Stretch kernel with Buster SE Linux userspace (particularly systemd) is an
unsupported configuration. It is not possible to get a SE Linux system with
Buster systemd and Stretch kernel to work correctly.